Drawing-pulley group for a wire-drawing machine for thin metal wires

ABSTRACT

A group of drawing pulleys arranged in a spiral path and having between the successive pulleys individual dies for progressively reducing the cross section of a wire drawn by the pulleys through the dies. The axes of the pulleys are disposed spaced along the spiral path and in parallel relationship. The pulleys are rotatably driven with the speed of rotation such that the speed of each pulley is higher than the preceding pulley and proportional to the elongation of the wire being drawn because of reduction of its diameter.

United States Patent 1191 1111 3,811,312

Pietroni May 21, 1974 DRAWING-PULLEY GROUP FOR A 413,889 10/1889 Beguz 72/280 WIREDRAWING MACHINE O THIN 1,973,596 9/1934 Yousey 72/289 METAL WIRES [75] Inventor: Piero Pietroni, Ascoli Piceno, Italy Primary Exami' 1e"'Charle$ Lanham Asszstant Examiner-M. J. Keenan [73] Assignee: Technofil S.p.A., Ascoli Piceno, Attorney, Agent, or Firm R0bert E. Bums; Emman Italy uel J. Lobato [22] Filed: Dec. 29, 1972 [30] Foreign Application Priority Data A group of drawing pulleys arranged in a spiral path Dec 3| 1971 [ml 33l97/71 and having between the successlve pulleys mdivldual v y d1es for progressively reducing the cross sect10n of a wire drawn by the pulleys through the dies. The axes 72/27gil72/l2/gz v of the pulleys are disposed spaced along the Spiral [58] d 281 path and in parallel relationship. The pulleys are rotat- 0 ea c ably driven with the speed of rotation such that the speed of each pulley is higher than the preceding pulley and proportional to the elongation of the wire [56] UNITE SX$ES SZqFENTS being drawn because of reduction of its diameter.

778,041 12/1904 Horton.. 72/280 5 Claims, 3 Drawing Figures DRAWING-PULLEY GROUP FOR A 1 WIRE-DRAWING MACHINE FOR THIN METAL WIRES BACKGROUND OF THE INVENTION The present invention refers in general to wiredrawing machines and, in particular, to a drawingpulley group for sliding wire-drawing machines for thin metal wires.

As known, there are numerous wire-drawing machines of the sliding type on the market, in which, by means of successive drawing steps, the diameter or section of the wire is notably reduced, arriving even at dimensions of the finished wire of the order of a few centesimals. At present, there are three different types of sliding wire-drawing machines on the market.

The first type comprises two driving shafts, each one being provided, in opposed directions with drawing pulleys of decreasing diameter, so that the wire passes alternately from one shaft to the other one and is coiled on pulleys of varying diameter. The drawing operation as such takes=place by means of suitable dies during the passing of the wire from one shaft to the other. Drawing machines of this type have numerous drawbacks such as, for example, the noteworthy vibrations the shafts are subjected to by the repeated coiling on and off of the wire. These vibrations, in some cases, may even cause breaking of the shafts. In addition, in similar drawing machines the coiling angle of the wire on each pulley is substantially constant at 180. This effect, too, is negative because, in order to obtain the right drawing effect of the wire, the specific pressure on the drawing pulley must be notably increased, causing increased wear of the pulley and imperfections of the drawn wire. In addition, the wire, then arriving, that when still at its maximum diameter, is coiled at once on a pulley of smaller diameter, resulting in a certain yield-stressing of the wire.

In another type of wire-drawing machine with single shafts, the drawing pulleys provided to receive the wire, are aligned in parallel rows. In this case, the wire is fully coiled for 360 onto each-drawing pulley, forming a coil, in which the points of arrival and end are in touch, with the therefrom resulting danger of breaking or damaging the coil turns. In addition, the sliding of the wire relative to the drawing pulley is made difficult, be-

cause of the excessive coiling angle of the wire pressing against the pulley. In this type of drawing machine, the coiling angle of the wire on the pulley remains constant with varying diameter of the wire, resulting in the working conditions becoming more critical for decreasing wire diameters.

A third type of wire-drawing machine, known as a single drawing pulley type. uses. to reduce the coiling angle of the wire on the pulleys, intermediate guide pulleys, resulting. obviously. in a rather bulky arrangement, a relatively high cost due to the doubling of the drawing and guide pulleys supporting shafts and the therefrom resulting dual motorization.

SUMMARY or THE INVENTION A principal object of the present invention to provide a drawing-pulley group for sliding drawing machines for metal wires, capable to reduce, if not eliminate, the above-mentioned troubles of the known wire-drawing machines.

It is another object of the present process to provide a drawing pulley group for wire-drawing machines of the type mentioned hereinabove, in which the drawing pulleys permit the reduction of the coiling angleof the wire on each single pulley and, at the same time, the progressive diminution of the coiling angle of the wire on the pulleys in function of the reduction of the diameter of the wire.

It is still another object of the present invention to provide a drawing-pulley groupfor wire-drawing machines of the above type, so constructedas' to reduce notably the bulk thereof, and to reduce to a minimum the stresses acting on the drawing shafts.

Another object is to provide a drawing-pulley group which comprises single pulleys fixed to as many shafts so that the arrangement permits the use of interchangeable pulleys of equal diameter and the coilage of the wire on sufficiently large diameter pulleys even during the first steps. The present invention comprises a group of drawing pulleys for wire-drawing machines of'the above type, having a supporting structure for a plurality for driven, rotating drawing pulleys receiving, one after the other, a metal wi're to be drawn. The axes of rotation of the pulleys are parallel one to'the other and suitably spaced. A die is positioned between two adjacent drawing pulleys to ensurea predetermined reduction of the diameter of the wire passing between the two pulleys. Each drawing pulley being so controlled as to rotate, relative to the preceding drawing pulley, at a higher speed proportional to the elongation of the wire because of the reduction of its diameter. The group is characterized by the drawing pulleys being arranged disposed along a spiral line or path. I

According to the arrangement, the coiling angle of the wire is always lower than 360, resulting in the almost complete elimination of any contact between the single turns. In addition, the coiling angle decreases progressively with the reduction in the diameter of the wire, because the beginning point is at the periphery of the spiral, ensuring therefrom optimum sliding conditions also on the last pulleys. Also, the wire is always coiled in the same direction of rotation, that is, in the technologically best condition and no transmission pulleys are required to decrease the coiling angle; a fact permitting a notable economy in cost, plant, operation and space.

The present invention provides in addition, a sliding wire-drawing machine for metal wires, equipped with a drawing pulley group as detailed hereinabove.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description refers to a drawing-pulley group according to the present process, fixed to a sliding-type wire-drawing machine complete with drawing desired, with a centralized unit for circulating the lubricant and coolant of the wire to be drawn. It is under- .stood that the arrangement of the drawing pulleys according to the present invention is not limited only to the machine of the mentioned type, but may be applied to other types of drawing machines, and this independently of the presence or absence of the annealing and re-reeling units on the same machine.

Referring now to FIG. 2, the drawing-pulley group according to the present invention is formed of a plurality of pulleys 1'4 with the axes of rotation in parallel and uniformly spaced one from the other. The pulleys 14 are substantially placed in a plane along a spiral path or line. FIG. 2 shows .also, that between the successive pulleys 14, there is always disposed a die 16 known per se, for the progressive reduction of the wire to be drawn.

The dies 16, known per se, are completely schematized, For the purpose of the present description, the

' phrase spiral line" indicates any type of line or path spirally turning one or more times around an assumed center point. The arrangement of the spiral of pulleys thus permits the reduction "of the coiling angle, beginning at the outmost pulley, that is, the pulley at the beginning of the spiral and ending at the innermost pulley,

that is the pulley at the end of the spiral. The coiling angle is the angle at the center of each single pulley l4 and the point, at which the wire leaves the pulley, measured in the direction of travel of the wire around the pulley. Suitable peripheral guide pulleys I 17 positioned around the spiral system of drawingpulleys 14, already mentioned, allow it, to shift the point of entry of the wire 15 to be drawn, to an intermediate drawing pulley, reducing in this manner the number of drawing steps the wire is subjected to, as a function of the original diameter of the wire or the finished diameter, it is desired to obtain. 7

In the example in FIG. 2, the wire 15, guided by the pulleys 17 and I7 in the upper left corner of the drawing, passes through a first die 16, is wound around the first drawing pulley 14 by an angle smaller than 360, and decreasing passes through a second die 16 to be rewound. always by an angle smaller than 360, but slightly larger than the first one, around the second drawing pulley l4, and so on, until it reaches the innermost idler pulley 14 of the spiral system. After which the wire I5 is returned to the next to last pulley and I leaves the machine (toward the right in FIG. 2), passing and on relatively large diameters, so as to maintain the I specific contact pressure between wire and pulley at an acceptable level and, in any case, at a level, which ensures a long working life of the pulleys.

In addition, the fact that the wire 15 enters the spiral system at any one of the pulleys and leaves it from any one of the inner pulleys, of the spiral ensures with the reduction of the wire diameter also the progressive reduction of the ensuring winding angle and optimum sliding conditions,eliminating also the contact between the ends of the wire coil on each pulley. In the given example, at the inlet pulley, we have thus a winding angle of 340, decreasingprogressively for each successive pulley to arrive at an angle of 300 at the last pulley. FIG. 3 shows clearly, in the enlarged section taken along section line IVIV of FIG 2, that each pulley 14 is supported at the end by a shaft 19, internally seated and guided, by means of rolling bearings 20, in an tubular element 21, welded to a supporting structure or frame 22 at the inside of the wire-drawing machine.

At the other end, as shown in FIG. 3 of the drawings, each shaft 19 is provided with two gear wheels 23 and 24. The larger-diameter gear wheel 23 is connected by means of a cogged belt 25 with the smaller-diameter gear wheel 24 of the preceding pulley 14, that is, upstream in the direction of travel of the wire. In this way, by suitable sizing the diameters of successive gear wheels, the increase in speed of successive pulleys 14, that is, downstream in the direction of travel of the wire, will be proportional to the elongation of the wire because of the reduction of its section. It is also possible, at the same time, to drive anyone of the shafts by means of an electric motor 26, automatically ensuring the rotation of all the other shafts.

FIG. 3 also shows, that each pulley 14 is slightly displaced toward the outside relative to the immediately preceding one, permitting in this way the perfect alignment of the wire with the dies 16 positioned between the successive pulleys. By way of example, it has been possible, with a wire-drawing machine provided with a system of drawing pulleys according to the present invention, to ensure a maximum number of twenty-two passages realized with single shafts and interchangeable I00 mm diameter drawing pulleys, keeping at the same time the overall dimensions of the machine at a mini mum. At the same time, as a function of the variability of the number of passages of the wire and its inlet diameter at any one of the pulleys 17 or 12, it has been possible to obtain, at the outlet, diameter variable from 0.2 to 0.05 mm, with a drawing speed in excess of m/sec.

It clearly results from the above description and the drawings, both by way of example without limiting effect, that we-have constructed a new system of drawing pulleys and dies for wire-drawing machines, ensuring without doubt advantages and performances, that are superior to the corresponding systems of the wireexample that shown in the lower left angle of FIG. 2,

the wire [5 will be subjected to a lower number of drawing steps than in the preceding case, with a therefrom resulting proportionally lesser reduction of diamdrawing machines presently known.

What we claim and desire to secure by letters patent is:

1. A drawing-pulley group for wire-drawing machines of the sliding type for thin metal wires, having a supporting structure for a plurality of rotatably driven drawing pulleys, on which a metal wire to be drawn is progressively wound, said drawing pulleys having spaced, parallel rotation axes a plurality of dies positioned individually between adjacent successive pulleys to ensure a predetermined reduction of the diameter of a wire passing in operation through the dies, means for driving each pulley at a speed which, relative to the preceding pulley progressively increases and proportional to the elongation of the wire due to the reduction of its cross section, and the drawing pulleys being arranged in a group and arranged defining a spiral.

2. A drawing-pulley group for wire-drawing machines according to claim 1, in which an outermost pulley is the inlet pulley for the wire to be drawn, and the innermost pulley is the outlet pulley for the drawn wire.

3. A drawing-pulley group for wire-drawing machines according to claim 1, including guide pulleys for the wire, positioned outside of the drawing-pulley spiral group and provided for guiding the wire to be drawn to any intermediate drawing pulley of the spiral group.

4. A drawing-pulley group for wire-drawing machines according to claim 3, in which each drawing pulley is slightly axially displacedto the outside relative to the immediately preceding drawing pulley.

5. A drawing-pulley group for wire-drawing machines according to claim 4, in which each drawing pulley is supported at one end, a single drive shaft for each pulley, the other end of each drive shaft having two gear wheels, a cogged belt connecting one gear wheel to the corresponding gear wheel pair of the preceding pulley and to that of the following pulley for series control of the individual pulleys. 

1. A drawing-pulley group for wire-drawing machines of the sliding type for thin metal wires, having a supporting structure for a plurality of rotatably driven drawing pulleys, on which a metal wire to be drawn is progressively wound, said drawing pulleys having spaced, parallel rotation axes a plurality of dies positioned individually between adjacent successive pulleys to ensure a predetermined reduction of the diameter of a wire passing in operation through the dies, means for driving each pulley at a speed which, relative to the preceding pulley progressively increases and proportional to the elongation of the wire due to the reduction of its cross section, and the drawing pulleys being arranged in a group and arranged defining a spiral.
 2. A drawing-pulley group for wire-drawing machines according to claim 1, in which an outermost pulley is the inlet pulley for the wire to be drawn, and the innermost pulley is the outlet pulley for the drawn wire.
 3. A drawing-pulley group for wire-drawing machines according to claim 1, including guide pulleys for the wire, positioned outside of the drawing-pulley spiral group and provided for guiding the wire to be drawn to any intermediate drawing pulley of the spiral group.
 4. A drawing-pulley group for wire-drawing machines according to claim 3, in which each drawing pulley is slightly axially displaced to the outside relative to the immediately preceding drawing pulley.
 5. A drawing-pulley group for wire-drawing machines according to claim 4, in which each drawing pulley is supported at one end, a single drive shaft for each pulley, the other end of each drive shaft having two gear wheels, a cogged belt connecting one gear wheel to the corresponding gear wheel pair of the preceding pulley and to that of the following pUlley for series control of the individual pulleys. 